Certain 3-oxo-2(halophenyl)-4,5,6,7-tetrahydro-v-triazolo{8 1,5a{9 -pyridines

ABSTRACT

A process for inhibiting plant growth comprising contacting a plant or its growth area with an effective amount of certain para-halophenyl substituted triazolines. A series of novel mesoionic para-halophenyl substituted triazolines. A novel process for preparing 3-phenyl-4-oxo-1,2,3-triazoline by contacting benzenediazoniumchloride and an Alpha -amino carboxylic acid and cyclodehydrating the triazene produced using acetic anhydride and pyridine.

United States Patent Abu-el-Haj et al.

3,894,036 July 8, 1975 CERTAIN 3-0XO-2(HALOPHENYL)-4,5,6,7-

TETRAHYDRO-V-TRIAZOLOl 1,5A1-

PYRIDINES inventors: Marwan J. Abu-eLHaj, Groton;

James W. McFarland, Lyme, both of Conn.

Assignee: Pfizer Inc., New York, N.Y. Filed: Sept. 10, 1973 Appl. No.: 395,713

Related U.S. Application Data Continuation-impart of Ser. No. 170,996, Aug. 11. 1971, abandoned.

U.S. Cl... 260/295 K; 260/306.8 F; 260/308 A;

260/294.9; 260/294.8 C; 71/92 Int. Cl. C07D 31/44 Field of Search 260/295 K References Cited OTHER PUBLICATIONS Reimlinger et al., Chem. Ber., 97 (12), pp. 3493-3502 (I964), Ger.

Primary Examiner-Alan L. Rotman Attorney, Agent, or Firm-Connolly and Hutz [57] ABSTRACT 6 Claims, N0 Drawings CERTAIN 3-OXO-2(HALOPHENYL))-4,5 ,6,7-TETRAHYDRO- V-TRIAZOLO[1,5A]-PYRIDINES CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of our copending application Ser. No. 170.996, filed Aug. 11, 197] and now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to the field of control of plant growth. In particular it relates to methods and compounds for killing weeds and a novel process for preparing such compounds.

The term weed is used in the present disclosure in its broadest sense, that is, a plant which persists in growing where it is not wanted. This use of the term is broad enough to include plants such as poison ivy or other plants plainly harmful to man and also otherwise desirable plants such as honeysuckle or lawn grasses growing in such places as driveways.

SUMMARY OF THE INVENTION atoms. By halogen is means chlorine, fluorine. bromine, or iodine. The preferred novel compounds of this invention are:

3-oxo-2-( 2,4-dichlorophenyl )-4,5,6,7-tetrahydro-vtriazolo l,5-a) pyridine; 3-oxo-2-(2,4-dibromophenyl)-4,5,6,7-tetrahydro-vtriazolo (1,5-a) pyridine; 3-oxo-2-(2,4,5-trichlorophenyl)-4,5,6,7-tetrahydrov-triazolo( l,5-a)pyridine; 3-oxo-2-(2,4,5-trichlorophenyl)-4,5,6,7-tetrahydrov-triazolo( l,5-a)pyridine;

3-oxo-2-( 2-chloro-4-bromophenyl )-4,5 ,6,7-

tetrahydro-v-triazolo( l ,5-a)pyridine.

The third object of the present invention is to provide a novel process for preparing 3-phenyl-4-oxo-l ,2,3- triazoles comprising contacting a benzenediazonium chloride with an a-amino carboxylic acid in at least equimolar proportions and in an aqueous solution and subsequently cyclodehydrating the resulting 1- carboxymethyl-3-phenyl-triazene so produced by treatment with acetic anhydride and pyridine in an inert solvent.

The compounds thus defined and thus prepared are effective as herbicides in both preand post-emergence applications. They are suitable for selective killing of specific groups of unwanted plants, and also for the total destruction of all plants in an area.

DETAILED DESCRIPTION OF THE INVENTION The compounds of this invention are prepared by a novel process. Previously, similar mesoionic triazole compounds were prepared by cyclodehydration procedures involving the condensation of benzenediazonium chloride with an amino acid ester (Potts and I-Iusain, J. Org. Chem. 35:3451, 1970).

We have now found that greater yields of the desired compounds are obtained if this condensation is carried wherein: R is hydrogen, halogen, methyl or nitro; R, is

III

out using the amino acid rather than the amino acid eshalogen; R is hydrogen. halogen, or nitro; R and R 65 ter.

are each hydrogen or halogen; and R is alkyl of from 2 to 5 carbon atoms or cycloalkyl of 5 to 6 carbon An example of such a reaction is shown in the scheme below:

R NaNO HCl Rt, R5 R5 2 N NCl 9 V VI H l R N-cri -coa y m, +1 0 l R (ca co) c/ riaine R5 COOH N 0 N N 11 ca I Y \N 2 N t l R5 5 VII I All substituents are as previously defined.

in this case a para-halogen substituted aniline (V) is reacted with nitrous acid in at least equimolar proportions to form the benzenediazoniumchloride (Vl). Compound V] is then reacted with an a-amino carboxylic acid in at least equimolar proportions and in an aqueous medium to form VII. The reaction up to this point is preferably carried out in the cold, at about 0C.

Compound V" is then dehydrated to form the desired compound I by suspending VII in ether or other inert solvents and then adding acetic anhydride followed by pyridine. This mixture is allowed to stand overnight or for a few days at room temperature. The crystalline product I may then be filtered and washed with ether, if desired.

The choice of anilines for use in the above reaction is governed by the product desired so long as the parahalogen atom is preserved and the other substituents follow the definitions previously set forth.

The choice of amino acids useful in the above reaction is also very broad. lf compounds of type I are desired, the amino acid used will be of the formula wherein R is alkyl of 2-5 carbon atoms or cycloalkyl of 5 to 6 carbon atoms as previously stated.

lf compounds of formula II are desired pipecolinic acid is used, for compounds of type [I] proline is used, and for type [V compounds 4-thiazolidinecarboxylic acid is used.

This novel process is generally applicable to the preparation of any 3-phenyl-4-oxo-l,2,3-triazoline and is effected by treating the corresponding benzenediazoniumchloride with the appropriate a-amino carboxylic acid in at least equimolar proportions and in an aqueous solution, and cyclodehydrating the resulting lcarboxymethyl-3-phenyl-triazene by treatment with acetic anhydride and pyridine in an inert solvent, preferably ether.

The 4-halophenyl herbicides of the present invention may include a variety of substituents on the halophenyl ring. This includes 4-chloro, -bromo, -fluoro or -iodophenyl groups having, for example, nitro, methyl, halogen, methoxy, trifluoromethyl, cyano, methylthio, and the like in the 2-, S-and/or 6-positions. Ordinarily we prefer phenyl having no more than 3 substituents in the interest of ease of preparation and cost. Preferred 4-halophenyl substituents are those defined above in formulae I, ll, Ill and IV.

The compounds of this invention may be used as suspensions, solutions, or dusts. The form of application depends upon the purpose for which the product is designed, but, in any case it should ensure a fine distribution of the active ingredient.

For the preparation of solutions to be sprayed directly on the plants, mineral oils such as diesel oil or kerosene, coal-tar oils, and other oils of animal or plant origin are suitable.

Aqueous formulations are preferred and may be prepared from emulsion concentrates, pastes, or wettable powders by adding water.

Dusts may be prepared by mixing or grinding the active compound with a suitable solid carrier.

The compounds of this invention may also be combined with known herbicidal agents if desired.

In the greenhouse and field testing of the compounds of this invention which is reported in the examples to follow, the compounds were prepared as aqueous suspensions and then applied both to soil in which seeds of crop plants and weeds had been planted and also to young plants. Results are given numerical values of from 0 for no effect to ID for all plants killed. The dosages used varying from 0.5 to 10 lbs. per acre are reported in the following examples for each compound tested.

The compounds of this invention are preferably to be used in such a way that a dose of from about 1-10 lbs. per acre of the active ingredient will be applied. Larger or smaller doses may of course be employed, but no especial benefit will be gained by such use.

The following examples are illustrative and in no way limit the scope of the appended claims.

EXAMPLE 1 In a 12 3 necked round bottom flask are added 162 g. (1 mole) of 2,4-diehloroaniline, 500 ml. concentrated HCl, and 2000 ml. H O. The aniline was dissolved by the aid of heating on a steam bath. The solution was cooled to about 0C., and 76 g. (1.1 mole) of sodium nitrite dissolved in 200 ml. of H 0, were added to it. The solution was stirred at /2 hour and then a saturated solution of urea was added until a negative test with starch paper was obtained. This solution was then slowly added (over a period of about 2 hours) to a cooled solution of pipecolinic acid (129 g.-l.0 mole) and triethylamine (416 m1.-3 mole) in 15 l. of water. The resulting mixture was stirred for A hour, after which the precipitated solid was filtered and washed with water. The cake was taken up in methylene chloride (1.5 l.) and the filtrate was extracted twice with methylene chloride (1 1.). The combined methylene chloride solutions were dried over anhydrous sodium sulfate and then evaporated in vacuo to afford 159 g. of an oil.

The oil was dissolved in 2 l. of ether. To this was added 200 ml. of acetic anhydride followed by 100 ml. of pyridine. The reaction mixture was allowed to stand at room temperature for 24 hours. The crystalline product was then filtered and washed with ether to yield 85 g. of a product with a melting point of l38-139C. The mother liquor was evaporated in vacuo to dryness. Upon addition of ether, 2| g. of the above product were obtained. A third crop of 15.5 g. of this product was also obtained upon concentration of the mother liquor. A total of 121.5 g. of anhydro-3- oxo-2-( 2,4-dichlorophenyl)-4,5 ,6 ,7-tetrahydropyrido- [1,2-C]-v-triazolinium hydroxide with a melting point of 138139C. was produced.

The above compound in an aqueous suspension was tested in the field in a standard pre-emergence test against Jimson weed at lb./acre as previously described, and was found to have a rating of 9 in this test.

EXAMPLES lI-LXIV 1n the Examples to follow, the compounds were prepared and tested as in Example 1 using the appropriately substituted aniline and the appropriate a-amino carboxylic acid.

Melting Effect on Example Point Pounds Jimson Weed No. Substitution C. lAcre Pre Post R, F R, H 3 R =Cl 183-184 2 l0 10 R, =Cl R, S-Cl 4 R Cl 240-242 2 9 10 R, =Cl R 6-C1 S R NO, 210-211 5 3 9 R, =Cl R, 6 R Br -97 5 9 10 R, Br R H 7 R H 174-176 l0 l0 9 R, =Cl R, 8 R CH, 151-152 5 9 7 R, C1 R, 9 R Cl 166-168 2 9 3 R, Br R 10 R=CH 155-157 10 10 10 R, Br R, H 11 R=Cl 213-214 10 10 10 R, =Cl R G-NO, 12 R=CH;, 166-[67 l0 l0 7 R, R, H 13 R=CH 171-172 5 3 10 Standard greenhouse herbicide tests were performed. Values of from 0 (no injury) to 10 (all plants killed).

Soil treated before emergence of seedling.

Plants treated after emergence from soil.

Melting Effect on Example Point Pounds Jimson Weed No. Substitution [Acre Pre Post 14 R=Br 172-176 10 10 R, Br R, H 15 R F 5 8 R, F H 16 R NO, 204-205 S 3 9 R, Cl 2 H 17 R Cl -136 5 7 R, C1 R S-Cl 18 R Cl 240-241 10 10 R, C] R, 6-C1 19 R=C1 188-190 10 10 10 R, Br R, H 20 R CH, 178-180 10 5 7 R, C1 R H 21 R=CH, 198-201 10 9 10 R, Br R, H

Example No.

Substitution -Continued Example No.

Substitution Effect On Jimson Weed Pre Post Melting Point Pounds lAcre R, =i-propy1 1 R 1 R, CH, R. H R: i-propyl R NO,

Example No.

Substitution Continued Melting Point C.

Pounds [Acre Effect On Jimson Weed Pre Post

i-propyl 1 l H t-butyl Example Compound lbs/ SOYB CORN MNGY PIGW BNGS YNSG No. No. acre Pre Post Pre Post Pre Post Pre Post Pre Post Pre Post 65 22 8 2 6 2 2 3 7 l0 4 0 l 66 l 8 4 9 3 4 6 9 9 l0 l0 8 5 3 67 3 8 2 ND 2 ND 3 ND 10 ND 3 ND 3 ND 68 2 5 0 0 0 0 0 l0 0 9 0 0 0 0 69 4 [0 ND ND 5 0 l0 l0 l0 9 9 8 5 3 not done What is claimed is:

l. A compound of the formula 'r Rh R1 R N O N l 1 Example Melting Pounds Effect on No. Substitution Point lAcre .limson Weed C. Pre Post 6l R,=Cl [60.5-162 10 l0 10 R Cl 4 H 62 R, Cl 203-204 10 10 I0 R Cl R 6-0 63 R. F [68-170 10 10 10 whetem R:l R is hydrogen, halogen, methyl, or mtro; R. H 64 R. 0 182-184 l0 i0 10 i halogen and R =Cl R 1s hydrogen, halogen, or mtro. RPS-Cl 2. 3-oxo-2-(2,4-dibromophenyl)-4,5,6,7-tetrahydro- EXAMPLES 6S69 v-triazolo( l ,5-a)pyridine.

3. 3-oxo-2-(2,4,5-trichlorophenyl)-4.5,6,7- tetrahydro-v-triaz0lo( l ,5-a)pyridine.

4. 3-oxo-2-(2,4,6-trichlorophenyl)-4,5,6,7- tetrahydro-v-traizolo( l ,5-a)pyridine.

5. 3-ox0-2-(2-chloro-4-bromophenyl)-4,5,6,7- tetrahydro-v-triazolo( l ,5-a)pyridine.

6. 3 oxo-2-(2,4-dichlorophenyl)-4,5,6,7-tetrahydrov-triazolo( l ,5-a)pyridine. 

1. A COMPOUND OF THE FORMULA
 2. 3-oxo-2-(2,4-dibromophenyl)-4,5,6,7-tetrahydro-v-triazolo(1,5-a)pyridine.
 3. 3-oxo-2-(2,4,5-trichlorophenyl)-4,5,6,7-tetrahydro-v-triazolo(1,5 -a)pyridine.
 4. 3-oxo-2-(2,4,6-trichlorophenyl)-4,5,6,7-tetrahydro-v-traizolo(1,5 -a)pyridine.
 5. 3-oxo-2-(2-chloro-4-bromophenyl)-4,5,6,7-tetrahydro-v-triazolo(1,5 -a)pyridine.
 6. 3-oxo-2-(2,4-dichlorophenyl)-4,5,6,7-tetrahydro-v-triazolo(1, 5-a)pyridine. 